Dust Sampling Instruments and Dust Standards in the United States of America for Asbestos.
Pneumoconiosis, Proceedings of the International Conference, Johannesburg 1969 1970:10-12
Dust sampling instruments and asbestos (1332214) standards used in the United States were discussed. Threshold limit values (TLVs) for asbestos were considered. The first TLV for asbestos established by the American Conference of Governmental Industrial Hygienists (ACGIH) was 5.0 million particles per cubic foot of air (mppcf). Samples were collected by impingers and counted by a light field counting technique. The continued occurrence of asbestosis in the 1960s and the increasing concern over the risk of asbestos related malignancies prompted a new look at the asbestos standard. The ACGIH proposed in 1968 that the asbestos TLV be lowered to 12 fibers per milliliter for fibers having lengths longer than 5 microns or 2mppcf time weighted average. Dust sampling instruments for asbestos were discussed. It was noted that a fiber count is a better index of asbestos exposure than total particulate count. A TLV based on limiting the number of fibers longer than 5 microns provides an index for controlling overall asbestos exposure. In applying the new recommended standard, the ACGIH has stipulated that air samples be collected on membrane filters and that the counting procedure use phase contrast illumination at 450x magnification. The author concludes that the new ACGIH standard will reduce the risk of asbestos related diseases among those exposed to asbestos to an insignificant level.
Asbestos-fibers; Particulates; Occupational-health; Health-protection; Analytical-instruments; Health-hazards; Air-sampling; Pulmonary-system-disorders; Microscopic-analysis; Occupational-exposure;
Pneumoconiosis, Proceedings of the International Conference, Johannesburg 1969